Salicylic Acid

* A versatile ingredient used as an acne treatment and exfoliant
* Also known as Beta Hydroxy Acid
* Read TIA's article on Beauty Safety for Pregnant Women: An Interview with Dr. Jason P. Rubin

Salicylic Acid is a Salicin, formed with Salicin is metabolized. It is considered to have aspirin-like, anti-inflammatory properties and is a popular ingredient in acne treatment formulas. Salicylic Acid is one of several beta hydroxy acids, and works as a keratolytic by exfoliating the skin, "causing the cells of the epidermis to shed more readily, preventing pores from clogging up, and allowing room for new cell growth" (Wikipedia). It is considered especially effective because of its ability to penetrate the follicle, clearing the pores of debris at a deeper level and reducing blockage and in turn, acne flare ups and breakouts, according to Acne.About.com. According to CosmeticsCop.com, citing an articles entitled "Preservatives in Cosmetics," it also has antimicrobial properties. It is also well documented that salicylic acid can improve skin thickness, barrier functions, and collagen production.

Functions of Salicylic Acid:

Salicylic Acid is a Salicin, formed with Salicin is metabolized. It is considered to have aspirin-like, anti-inflammatory properties and is a popular ingredient in acne treatment formulas. Salicylic Acid is one of several beta hydroxy acids, and works as a keratolytic by exfoliating the skin, "causing the cells of the epidermis to shed more readily, preventing pores from clogging up, and allowing room for new cell growth" (Wikipedia). It is considered especially effective because of its ability to penetrate the follicle, clearing the pores of debris at a deeper level and reducing blockage and in turn, acne flare ups and breakouts, according to Acne.About.com. According to CosmeticsCop.com, citing an articles entitled "Preservatives in Cosmetics," it also has antimicrobial properties. It is also well documented that salicylic acid can improve skin thickness, barrier functions, and collagen production.

Salicylic acid is also used in several dandruff shampoos, and is also an ingredient known to treat psoriasis, calluses, corns, keratosis pilaris, and warts. In wart-removal medications, it is used in concentrations ranging from 8 - 12%. However, as an exfoliant, it is used in concentrations no higher than 2%, and is considered more gentle than AHAs. Salicylic Acid is seen in a wide range of products, including moisturizers, skin cleansing products, shampoos, as well as skin care, hair care, suntan and sunscreen products, and in mouthwashes (CosmeticsInfo.org).

Salicylic Acid is FDA approved for inclusion in OTC acne drug products, and the CIR concluded that Salicylic Acid was “safe as used when formulated to avoid skin irritation and when formulated to avoid increasing the skin's sun sensitivity, or, when increased sun sensitivity would be expected, directions for use include the daily use of sun protection.”

Safety Measures/Side Effects of Salicylic Acid:

Although Salicylic Acid is a widely used ingredient, there are three primary concerns regarding its use: increased sun sensitivity (e.g., UV radiation induced skin damage), skin irritation, and reproductive and developmental toxicity. The Material Safety Data Sheet notes that it "Harmful by inhalation, ingestion and through skin absorption. Irritant. Chronic effects: laboratory experiments have shown mutagenic effects. May cause harm to the unborn child. May act as a sensitizer."

Known and well-documented side effects of products containing Salicylic Acid include stinging, burning, dryness, peeling, and flaking of the skin, caused by the keratolytic process of shedding cells. People using formulas containing this ingredient should use an oil-free moisturizer in conjunction with the cleanser or acne treatment to combat these side effects, although it should be expected that they will increase with usage and then peak and decrease within two to three weeks (Acne.About.com). According to the Mayo Clinic, people using products containing Salicylic Acid should not apply the following on the same area: abrasive soaps or cleansers, alcohol-containing preparations, any other topical acne preparation or preparation containing a peeling agent (for example, benzoyl peroxide, resorcinol, sulfur, or tretinoin [vitamin A acid]), cosmetics or soaps that dry the skin, medicated cosmetics, other topical medicine for the skin.

Salicylic Acid is also known to increase the skin’s sun sensitivity by 50%. All exfoliants that remove layers of the dermis expose the skin to more UV rays, therefore increasing UV radiation. A study done by the FDA and National Toxicology Program "was designed to determine if Salicylic Acid increases the risk of UV light induced skin tumors. Although the strain of mice used in this study was very sensitive to developing skin tumors when exposed to UV light, Salicylic Acid did not increase skin tumors." However, the FDA still recommends using a sunscreen containing SPF 30 or more in conjunction with any product containing Salicylic Acid. Use of concentrated solutions of salicylic acid may also cause hyperpigmentation on those with darker skin types.

Although reproductive and developmental toxicity have been associated with exposures to large, therapeutic serum concentrations of Salicylic Acid (as a metabolite of aspirin), the CIR Expert Panel concluded that topical use of Salicylic Acid would not produce serum levels of Salicylic Acid that would result in a reproductive or developmental toxicity risk (CosmeticsInfo.org). The Mayo Clinic also found that there were no "adequate studies in women for determining infant risk when using this medication during breastfeeding." Pregnant and nursing women should still use caution when applying products containing Salicylic Acid, especially over large portions of their body, as in body lotions or scrubs. Salicylic Acid take orally (as in aspirin) has not been shown to increase the number of malformations if used during the first trimester, but used late in pregnancy it has been associated with bleeding, especially intracranial bleeding, although this reaction does not correlate to the levels of exposure in topical application.

It is considered a high hazard by the Cosmetics Database. It notes concerns regarding cancer, developmental and reproductive toxicity, enhanced skin absorption, neurotoxicity, organ system toxicity, and irritation. It also considers this ingredient a penetration enhancer.